A semiconductor manufacturing apparatus is available as one example of a substrate processing apparatus. Furthermore, a vertical apparatus is known as one example of the semiconductor manufacturing apparatus. The semiconductor manufacturing apparatus of this kind includes a substrate holder (boat) configured to hold substrates (wafers) in multiple stages. A plurality of substrates is transferred from a transfer chamber to the substrate holder. While holding the substrates in place, a process gas is supplied from a nozzle installed in a process chamber of a processing furnace, thereby processing the substrates.